1. Field of the Invention
The present general inventive concept relates to an optical member coupling device, and, more particularly, to an optical member coupling device that is capable of stably maintaining the coupling state of an optical member, coupled to a coupling position by an adhesive, even when the optical member contracts or expands due to the temperature change, and an optical scanning apparatus including the same.
2. Description of the Related Art
Generally, an optical scanning apparatus is used in an electro-photographic image forming machine to scan a beam to a photoconductor, according to an image signal, such that an electrostatic latent image is formed on the photoconductor. The optical scanning apparatus includes a light source to generate a beam according to an image signal, a collimator lens that converts the beam, generated from the light source, into a beam parallel to an optical axis, i.e., a collimated beam, a cylindrical lens that converts the collimated beam into a beam parallel to a sub-scanning direction, i.e., a linear beam, a polygon mirror to deflect the linear beam within a specific angle range, and an F-theta lens that converges the beam, reflected by the polygon mirror, to the surface of a photoconductor. These components are mounted to a single base member to constitute a single module.
In order to precisely form an electrostatic latent image on the photoconductor according to an image signal, the optical members, such as the collimator lens, the cylindrical lens, the polygon mirror, and the F-theta lens, must be accurately and securely mounted to a housing. Also, the change in installation position of the optical members due to environmental factors, such as the temperature change, must be prevented.
Typically, the optical members may be coupled to the housing a coupling member, such as a screw, or an adhesive. The coupling method using the coupling member, such as a screw increases the number of components, with the result that the manufacturing costs of the optical scanning apparatus increases, and the weight of the optical scanning apparatus also increases.
A coupling method using an adhesive is described in Japanese Patent Application Publication No. 2004-133073 (published Apr. 30, 2004), which provides an optical apparatus constructed in a structure in which a glass substrate is coupled using an adhesive.
In the described optical apparatus, four corners of a rectangular glass substrate are joined to a spacer by a high-elasticity adhesive, such that the glass substrate is coupled to the spacer, and a low-elasticity adhesive is applied to the edge of the glass substrate such that the glass substrate is joined to the spacer.
In the conventional optical apparatus, however, the coefficient of the thermal expansion of the glass substrate is different from that of the spacer, made of resin. Consequently, when the temperature changes, excessive thermal stress occurs at the interface between the glass substrate and the spacer, with the result that the glass substrate becomes separated from the spacer.